Introduction: Bariatric surgery aims for optimal patient outcomes, often evaluated through the percentage total weight loss (%TWL). Quality registries employ funnel plots for outcome comparisons between hospitals. However, funnel plots are traditionally used for dichotomous outcomes, requiring %TWL to be dichotomized, potentially limiting feedback quality. This study evaluates whether a funnel plot around the median %TWL has better discriminatory performance than binary funnel plots for achieving at least 20% and 25% TWL. Methods: All hospitals performing bariatric surgery were included from the Dutch Audit for Treatment of Obesity. A funnel plot around the median was constructed using 5-year %TWL data. Hospitals positioned above the 95% control limit were colored green and those below red. The same hospitals were plotted in the binary funnel plots for 20% and 25% TWL and colored according to their performance in the funnel plot around the median. We explored the hospital’s procedural mix in relation to %TWL performance as possible explanatory factors. Results: The median-based funnel plot identified four underperforming and four outperforming hospitals, while only one underperforming and no outperforming hospitals were found with the binary funnel plot for 20% TWL. The 25% TWL binary funnel plot identified two underperforming and three outperforming hospitals. The proportion of sleeve gastrectomies performed per hospital may explain part of these results as it was negatively associated with median %TWL (β = − 0.09, 95% confidence interval [− 0.13 to − 0.04]). Conclusion: The funnel plot around the median discriminated better between hospitals with significantly worse and better performance than funnel plots for dichotomized %TWL outcomes. Graphical Abstract: (Figure presented.)

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Introduction
Different limb lengths are used in Roux-en-Y gastric bypass (RYGB) surgery, as there is no consensus which limb length strategy has the best outcomes. The biliopancreatic limb (BPL) is thought to play an important role in achieving weight loss and associated comorbidity resolution. The objective of this study was to assess the impact of a longer BPL on weight loss and comorbidity improvement at 5 years after primary RYGB.

Methods
All patients aged ≥ 18 years undergoing primary RYGB between 2014–2017 with registered follow-up 5 years after surgery were included. Long BPL was defined as BPL ≥ 100 cm and short BPL as BPL < 100 cm. The primary outcome was achieving at least 25% total weight loss (TWL) at 5 years. Secondary outcomes included absolute %TWL and improvement of comorbidities. A propensity score matched logistic and linear regression was used to estimate the difference in outcomes between patients with long and short BPL.

Results
At 5 years, long BPL had higher odds to achieve ≥ 25% TWL (odds ratio (OR) 1.19, 95% confidence interval (CI) [1.01 – 1.41]) and was associated with 1.26% higher absolute TWL (β = 1.26, 95% CI [0.53 – 1.99]). Furthermore, long BPL was more likely to result in improved diabetes mellitus (OR = 2.17, 95% CI [1.31 – 3.60]) and hypertension (OR = 1.45, 95% CI [1.06 – 1.99]).

Conclusion
Patients undergoing RYGB with longer BPL achieved higher weight loss and were more likely to achieve improvement of comorbidities at 5 years.@en

Background: Risk-prediction tools can support doctor–patient (shared) decision making in clinical practice by providing information on complication risks for different types of bariatric surgery. However, external validation is imperative to ensure the generalizability of predictions in a new patient population. Objective: To perform an external validation of the risk-prediction model for serious complications from the Michigan Bariatric Surgery Collaborative (MBSC) for Dutch bariatric patients using the nationwide Dutch Audit for Treatment of Obesity (DATO). Setting: Population-based study, including all 18 hospitals performing bariatric surgery in the Netherlands. Methods: All patients registered in the DATO undergoing bariatric surgery between 2015 and 2020 were included as the validation cohort. Serious complications included, among others, abdominal abscess, bowel obstruction, leak, and bleeding. Three risk-prediction models were validated: (1) the original MBSC model from 2011, (2) the original MBSC model including the same variables but updated to more recent patients (2015–2020), and (3) the current MBSC model. The following predictors from the MBSC model were available in the DATO: age, sex, procedure type, cardiovascular disease, and pulmonary disease. Model performance was determined using the area under the curve (AUC) to assess discrimination (i.e., the ability to distinguish patients with events from those without events) and a graphical plot to assess calibration (i.e., whether the predicted absolute risk for patients was similar to the observed prevalence of the outcome). Results: The DATO validation cohort included 51,291 patients. Overall, 986 patients (1.92%) experienced serious complications. The original MBSC model, which was extended with the predictors “GERD (yes/no),” “OSAS (yes/no),” “hypertension (yes/no),” and “renal disease (yes/no),” showed the best validation results. This model had a good calibration and an AUC of .602 compared with an AUC of .65 and moderate to good calibration in the Michigan model. Conclusion: The DATO prediction model has good calibration but moderate discrimination. To be used in clinical practice, good calibration is essential to accurately predict individual risks in a real-world setting. Therefore, this model could provide valuable information for bariatric surgeons as part of shared decision making in daily practice.

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Background: Literature remains scarce on patients experiencing weight recurrence after initial adequate weight loss following primary bariatric surgery. Therefore, this study compared the extent of weight recurrence between patients who received a Sleeve Gastrectomy (SG) versus Roux-en-Y gastric bypass (RYGB) after adequate weight loss at 1-year follow-up. Methods: All patients undergoing primary RYGB or SG between 2015 and 2018 were selected from the Dutch Audit for Treatment of Obesity. Inclusion criteria were achieving ≥ 20% total weight loss (TWL) at 1-year and having at least one subsequent follow-up visit. The primary outcome was ≥ 10% weight recurrence (WR) at the last recorded follow-up between 2 and 5 years, after ≥ 20% TWL at 1-year follow-up. Secondary outcomes included remission of comorbidities at last recorded follow-up. A propensity score matched logistic regression analysis was used to estimate the difference between RYGB and SG. Results: A total of 19.762 patients were included, 14.982 RYGB and 4.780 SG patients. After matching 4.693 patients from each group, patients undergoing SG had a higher likelihood on WR up to 5-year follow-up compared with RYGB [OR 2.07, 95% CI (1.89–2.27), p < 0.01] and less often remission of type 2 diabetes [OR 0.69, 95% CI (0.56–0.86), p < 0.01], hypertension (HTN) [OR 0.75, 95% CI (0.65–0.87), p < 0.01], dyslipidemia [OR 0.44, 95% CI (0.36–0.54), p < 0.01], gastroesophageal reflux [OR 0.25 95% CI (0.18–0.34), p < 0.01], and obstructive sleep apnea syndrome (OSAS) [OR 0.66, 95% CI (0.54–0.8), p < 0.01]. In subgroup analyses, patients who experienced WR after SG but maintained ≥ 20%TWL from starting weight, more often achieved HTN (44.7% vs 29.4%), dyslipidemia (38.3% vs 19.3%), and OSAS (54% vs 20.3%) remission compared with patients not maintaining ≥ 20%TWL. No such differences in comorbidity remission were found within RYGB patients. Conclusion: Patients undergoing SG are more likely to experience weight recurrence, and less likely to achieve comorbidity remission than patients undergoing RYGB.

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Purpose: Hospitals performing a certain bariatric procedure in high volumes may have better outcomes. However, they could also have worse outcomes for some patients who are better off receiving another procedure. This study evaluates the effect of hospital preference for a specific type of bariatric procedure on their overall weight loss results. Methods: All hospitals performing bariatric surgery were included from the nationwide Dutch Audit for Treatment of Obesity. For each hospital, the expected (E) numbers of sleeve gastrectomy (SG), Roux-en-Y gastric bypass (RYGB), and one-anastomosis gastric bypass (OAGB) were calculated given their patient-mix. These were compared with the observed (O) numbers as the O/E ratio in a funnel plot. The 95% control intervals were used to identify outlier hospitals performing a certain procedure significantly more often than expected given their patient-mix (defined as hospital preference for that procedure). Similarly, funnel plots were created for the outcome of patients achieving ≥ 25% total weight loss (TWL) after 2 years, which was linked to each hospital’s preference. Results: A total of 34,558 patients were included, with 23,154 patients completing a 2-year follow-up, of whom 79.6% achieved ≥ 25%TWL. Nine hospitals had a preference for RYGB (range O/E ratio [1.09–1.53]), with 1 having significantly more patients achieving ≥ 25%TWL (O/E ratio [1.06]). Of 6 hospitals with a preference for SG (range O/E ratio [1.10–2.71]), one hospital had significantly fewer patients achieving ≥ 25%TWL (O/E ratio [0.90]), and from two hospitals with a preference for OAGB (range O/E ratio [4.0–6.0]), one had significantly more patients achieving ≥ 25%TWL (O/E ratio [1.07]). One hospital had no preference for any procedure but did have significantly more patients achieving ≥ 25%TWL (O/E ratio [1.10]). Conclusion: Hospital preference is not consistently associated with better overall weight loss results. This suggests that even though experience with a procedure may be slightly less in hospitals not having a preference, it is still sufficient to achieve similar weight loss outcomes when surgery is provided in centralized high-volume bariatric institutions. Graphical Abstract: [Figure not available: see fulltext.]@en

Background: Primary laparoscopic adjustable gastric band (LAGB) has high rates of patients not achieving the desired weight loss, and it remains unclear which bariatric conversion procedure gives better results. Objective: To compare weight loss among patients undergoing conversion one-anastomosis gastric bypass (cOAGB) and conversion Roux-en-Y gastric bypass (cRYGB) after a failed LAGB. Setting: Nationwide population-based study including all 18 hospitals providing metabolic and bariatric surgery. Methods: Patients with a failed primary LAGB who underwent a cRYGB or cOAGB between January 1, 2015, and December 31, 2019, were selected from the Dutch Audit for Treatment of Obesity. The primary outcome was not achieving ≥20% total weight loss (TWL) at 1-year and up to 5-year follow-up. Secondary outcomes included postoperative complications, defined as Clavien-Dindo ≥III within 30 days, and co-morbidity remission. A propensity score matched logistic and Poisson regression model was used to estimate the difference in patients not achieving ≥20% TWL between cRYGB and cOAGB. Results: A total of 615 (78.7%) patients underwent cRYGB, and 166 (21.3%) patients underwent cOAGB, with 163 patients successfully matched. Both groups had similar rates of patients not achieving ≥20% TWL at 1 year (odds ratio [OR] = .64, 95% confidence interval [CI]: .38–1.05). However, a sensitivity analysis showed that patients undergoing cOAGB had lower rates of patients not achieving ≥20% TWL up to 5-year follow-up (rate ratio = .69, 95% CI: .51–.95, P < .05). Patients undergoing cOAGB were less likely to achieve hypertension remission (OR = .22, 95% CI: .07–.66). There were no significant differences between groups in postoperative complications (OR = .39, 95% CI: .07–2.06, P > .05). Conclusion: This matched nationwide study suggests that the cOAGB has similar short-term weight loss outcomes but potentially better long-term weight loss results than cRYGB. Therefore, cOAGB could provide a reliable alternative but needs to be substantiated in future long-term studies.@en

Introduction: Pooling population-based data from all national bariatric registries may provide international real-world evidence for outcomes that will help establish a universal standard of care, provided that the same variables and definitions are used. Therefore, this study aims to assess the concordance of variables across national registries to identify which outcomes can be used for international collaborations. Methods: All 18 countries with a national bariatric registry who contributed to The International Federation for the Surgery of Obesity and Metabolic Disorders (IFSO) Global Registry report 2019 were requested to share their data dictionary by email. The primary outcome was the percentage of perfect agreement for variables by domain: patient, prior bariatric history, screening, operation, complication, and follow-up. Perfect agreement was defined as 100% concordance, meaning that the variable was registered with the same definition across all registries. Secondary outcomes were defined as variables having “substantial agreement” (75–99.9%) and “moderate agreement” (50–74.9%) across registries. Results: Eleven registries responded and had a total of 2585 recorded variables that were grouped into 250 variables measuring the same concept. A total of 25 (10%) variables have a perfect agreement across all domains: 3 (18.75%) for the patient domain, 0 (0.0%) for prior bariatric history, 5 (8.2%) for screening, 6 (11.8%) for operation, 5 (8.8%) for complications, and 6 (11.8%) for follow-up. Furthermore, 28 (11.2%) variables have substantial agreement and 59 (23.6%) variables have moderate agreement across registries. Conclusion: There is limited uniform agreement in variables across national bariatric registries. Further alignment and uniformity in collected variables are required to enable future international collaborations and comparison. Graphical abstract: [Figure not available: see fulltext.]@en

Background: Bariatric surgery among patients with obesity and type 2 diabetes (T2D) can induce complete remission. However, it remains unclear whether sleeve gastrectomy (SG) or Roux-en-Y gastric bypass (RYGB) has better T2D remission within a population-based daily practice. Objectives: To compare patients undergoing RYGB and SG on the extent of T2D remission at the 1-year follow-up. Setting: Nationwide, population-based study including all 18 hospitals in the Netherlands providing metabolic and bariatric surgery. Methods: Patients undergoing RYGB and SG between October 2015 and October 2018 with 1 year of complete follow-up data were selected from the mandatory nationwide Dutch Audit for Treatment of Obesity (DATO). The primary outcome is T2D remission within 1 year. Secondary outcomes include ≥20% total weight loss (TWL), obesity-related co-morbidity reduction, and postoperative complications with a Clavien-Dindo (CD) grade ≥III within 30 days. We compared T2D remission between RYGB and SG groups using propensity score matching to adjust for confounding by indication. Results: A total of 5015 patients were identified from the DATO, and 4132 (82.4%) had completed a 1-year follow-up visit. There were 3350 (66.8%) patients with a valid T2D status who were included in the analysis (RYGB = 2623; SG = 727). RYGB patients had a lower body mass index than SG patients, but were more often female, with higher gastroesophageal reflux disease and dyslipidemia rates. After adjusting for these confounders, RYGB patients had increased odds of achieving T2D remission (odds ratio [OR], 1.54; 95% confidence interval [CI], 1.14–2.1; P < .01). Groups were balanced after matching 695 patients in each group. After matching, RYGB patients still had better odds of T2D remission (OR, 1.91; 95% CI, 1.27–2.88; P < .01). Also, significantly more RYGB patients had ≥20%TWL (OR, 2.71; 95% CI, 1.96–3.75; P < .01) and RYGB patients had higher dyslipidemia remission rates (OR, 1.96; 95% CI, 1.39–2.76; P < .01). There were no significant differences in CD ≥III complications. Conclusion: Using population-based data from the Netherlands, this study shows that RYGB leads to better T2D remission rates at the 1-year follow-up and better metabolic outcomes for patients with obesity and T2D undergoing bariatric surgery in daily practice.@en

Background: Current studies mainly focus on total weight loss and comorbidity reduction. Only a few studies compare Quality of Life (QoL) after sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB). This study was conducted to examine the extent of improvement in QoL on different domains after primary bariatric surgery and compare these results to Dutch reference values. Methods: The study included prospectively collected data from patients who underwent primary bariatric surgery in five Dutch hospitals. The RAND-36 questionnaire was used to measure the patient’s QoL; preoperatively and twelve months postoperatively. Postoperative scores were compared to Dutch reference values, standardized for age, using t-test. A difference of more than 5% was considered a minimal important difference. A multivariate linear regression analysis was used to compare SG and RYGB on the extent of improvement, adjusted for case-mix factors. Results: In total, 4864 patients completed both the pre- and postoperative questionnaire. Compared with Dutch reference values, patients postoperatively reported clinically relevant better physical functioning (RYGB + 6.8%), physical role limitations (SG + 5.6%; RYGB + 6.2%) and health change (SG + 77.1%; RYGB + 80.0%), but worse general health perception (SG − 22.8%; RYGB − 17.0%). Improvement in QoL was similar between SG and RYGB, except for physical functioning (β 2.758; p-value 0.008) and general health perception (β 2.607; p-value < 0.001) for which RYGB patients improved more. Conclusions: SG and RYGB patients achieved a better postoperative score in physical functioning, physical role limitations and health change compared to Dutch reference values, and a worse score in general health perception.@en